diff --git a/swh/storage/api/client.py b/swh/storage/api/client.py
--- a/swh/storage/api/client.py
+++ b/swh/storage/api/client.py
@@ -3,6 +3,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+import warnings
 
 from swh.core.api import SWHRemoteAPI
 
@@ -133,8 +134,17 @@
     def origin_add_one(self, origin):
         return self.post('origin/add', {'origin': origin})
 
-    def origin_visit_add(self, origin, ts):
-        return self.post('origin/visit/add', {'origin': origin, 'ts': ts})
+    def origin_visit_add(self, origin, date, *, ts=None):
+        if ts is None:
+            if date is None:
+                raise TypeError('origin_visit_add expected 2 arguments.')
+        else:
+            assert date is None
+            warnings.warn("argument 'ts' of origin_visit_add was renamed "
+                          "to 'date' in v0.0.109.",
+                          DeprecationWarning)
+            date = ts
+        return self.post('origin/visit/add', {'origin': origin, 'date': date})
 
     def origin_visit_update(self, origin, visit_id, status, metadata=None):
         return self.post('origin/visit/update', {'origin': origin,
diff --git a/swh/storage/storage.py b/swh/storage/storage.py
--- a/swh/storage/storage.py
+++ b/swh/storage/storage.py
@@ -9,6 +9,7 @@
 import datetime
 import itertools
 import json
+import warnings
 
 import dateutil.parser
 import psycopg2
@@ -898,12 +899,13 @@
         return None
 
     @db_transaction()
-    def origin_visit_add(self, origin, ts, db=None, cur=None):
+    def origin_visit_add(self, origin, date=None, db=None, cur=None, *,
+                         ts=None):
         """Add an origin_visit for the origin at ts with status 'ongoing'.
 
         Args:
             origin: Visited Origin id
-            ts: timestamp of such visit
+            date: timestamp of such visit
 
         Returns:
             dict: dictionary with keys origin and visit where:
@@ -913,12 +915,22 @@
             - ts (datetime.DateTime): the visit date
 
         """
-        if isinstance(ts, str):
-            ts = dateutil.parser.parse(ts)
+        if ts is None:
+            if date is None:
+                raise TypeError('origin_visit_add expected 2 arguments.')
+        else:
+            assert date is None
+            warnings.warn("argument 'ts' of origin_visit_add was renamed "
+                          "to 'date' in v0.0.109.",
+                          DeprecationWarning)
+            date = ts
+
+        if isinstance(date, str):
+            date = dateutil.parser.parse(date)
 
         return {
             'origin': origin,
-            'visit': db.origin_visit_add(origin, ts, cur)
+            'visit': db.origin_visit_add(origin, date, cur)
         }
 
     @db_transaction()
@@ -967,7 +979,8 @@
             origin: The occurrence's origin (identifier).
 
         Returns:
-            The information on that particular (origin, visit)
+            The information on that particular (origin, visit) or None if
+            it does not exist
 
         """
         ori_visit = db.origin_visit_get(origin, visit, cur)
diff --git a/swh/storage/tests/test_storage.py b/swh/storage/tests/test_storage.py
--- a/swh/storage/tests/test_storage.py
+++ b/swh/storage/tests/test_storage.py
@@ -1006,7 +1006,7 @@
         # when
         origin_visit1 = self.storage.origin_visit_add(
             origin_id,
-            ts=self.date_visit2)
+            date=self.date_visit2)
 
         # then
         self.assertEqual(origin_visit1['origin'], origin_id)
@@ -1031,15 +1031,15 @@
 
         origin_visit1 = self.storage.origin_visit_add(
             origin_id,
-            ts=self.date_visit2)
+            date=self.date_visit2)
 
         origin_visit2 = self.storage.origin_visit_add(
             origin_id,
-            ts=self.date_visit3)
+            date=self.date_visit3)
 
         origin_visit3 = self.storage.origin_visit_add(
             origin_id2,
-            ts=self.date_visit3)
+            date=self.date_visit3)
 
         # when
         visit1_metadata = {
@@ -1111,14 +1111,14 @@
 
         origin_visit1 = self.storage.origin_visit_add(
             origin_id,
-            ts=self.date_visit2)
+            date=self.date_visit2)
 
         self.storage.snapshot_add(origin_id, origin_visit1['visit'],
                                   self.snapshot)
 
         # Add some other {origin, visit} entries
-        self.storage.origin_visit_add(origin_id, ts=self.date_visit3)
-        self.storage.origin_visit_add(origin_id2, ts=self.date_visit3)
+        self.storage.origin_visit_add(origin_id, date=self.date_visit3)
+        self.storage.origin_visit_add(origin_id2, date=self.date_visit3)
 
         # when
         visit1_metadata = {